Refactor Dockerfile to use a separate lint stage with a pinned
golangci-lint v2.11.3 Docker image instead of installing
golangci-lint via curl in the builder stage. This follows the
pattern used by sneak/pixa.
Changes:
- Dockerfile: separate lint stage using golangci/golangci-lint:v2.11.3
(Debian-based, pinned by sha256) with COPY --from=lint dependency
- Bump Go from 1.24 to 1.26.1 (golang:1.26.1-bookworm, pinned)
- Bump golangci-lint from v1.64.8 to v2.11.3
- Migrate .golangci.yml from v1 to v2 format (same linters, format only)
- All Docker images pinned by sha256 digest
- Fix all lint issues from the v2 linter upgrade:
- Add package comments to all packages
- Add doc comments to all exported types, functions, and methods
- Fix unchecked errors (errcheck)
- Fix unused parameters (revive)
- Fix gosec warnings (MaxBytesReader for form parsing)
- Fix staticcheck suggestions (fmt.Fprintf instead of WriteString)
- Rename DeliveryTask to Task to avoid stutter (delivery.Task)
- Rename shadowed builtin 'max' parameter
- Update README.md version requirements
- Fan out all targets for an event in parallel goroutines (fire-and-forget)
- Add per-target circuit breaker for retry targets (closed/open/half-open)
- Circuit breaker trips after 5 consecutive failures, 30s cooldown
- Open circuit skips delivery and reschedules after cooldown
- Half-open allows one probe delivery to test recovery
- HTTP/database/log targets unaffected (no circuit breaker)
- Recovery path also fans out in parallel
- Update README with parallel delivery and circuit breaker docs
